Jenna Fischer: Why I’m ‘Looking Forward’ to Two Kids

Jenna Fischer may have just gone public with her pregnancy announcement, but the final countdown to welcoming her second child is well underway.

“I’m almost in my third trimester, so we’re in the homestretch already,” Fischer, 39, told PEOPLE Friday at the QVC Red Carpet Style event. “I know the news just came out, but it’s old news to us!”

While she is “looking forward to the excitement and challenge of adding another person,” to her family, the actress admits she’s a little unsure of what the future holds.

“Everyone’s telling me one plus one does not equal two. One plus one feels like four,” Fischer — who knows the sex of the baby but is keeping it private — says.

“My sister just had her second child so I’ve been calling her for a lot of advice [on] how to juggle the needs of two children.”

She adds, “I’m taking a good amount of time off right now to be a mom and grow my family, so I’m really just looking forward to getting to do that.”

Although she craved carbs while pregnant with son Weston Lee, the mom-to-be has fine-tuned her healthy habits this time around. In between her weekly “hiking date” with former Office costarAngela Kinsey, Fischer finds herself reaching for fresh foods.

“It’s been all fruits or crisp vegetables or salads,” she says. “I’ve been eating a salad a day — if I could have salad all of the time, I would love it!”

As for her 2½-year-old son, not only will he reach a major milestone soon — becoming a big brother! — but the toddler has been busy showing off his musical talents.

“He’s a very good drummer. He loves drumming,” Fischer says. “The other day he said to me, out of the blue, ‘Mom, “Paradise City” has a great beat.’ I was like, ‘”Paradise City” does have a great beat!'”